1. Field of the Invention
The present invention relates to an information processing apparatus and an information processing method for a recording apparatus that records an image on a recording medium using a recording head.
2. Description of the Related Art
A recording apparatus is a device that records an image (including characters and symbols) on a recording medium, such as paper, based on recording information. Such a recording apparatus may be used as a printer, a copying machine, or as an output device of an integrated electronic device, where the integrated electronic device includes a computer and a word processor or a workstation. The recording apparatus is classified into an inkjet type, a wire dot type, a thermal type, and a laser beam type according to the employed recording method.
Among the various types of recording apparatuses, the inkjet type recording apparatus (i.e., an inkjet recording apparatus) employs an inkjet recording head (hereinafter referred to as a recording head) as a recording unit. The inkjet recording apparatus records by discharging ink from discharge ports in the recording head to the recording medium.
Such an inkjet recording apparatus is beneficial in that the size of the recording head easily can be reduced, and a high-quality image can be formed at high speed. Further, the inkjet recording apparatus is capable of recording on plain paper without a need for special processing, so that running cost is low.
Furthermore, since the inkjet recording apparatus employs a non-impact printing method, little noise is generated. Moreover, it is easy for the inkjet recording apparatus to form a color image using a variety of inks colors, and to record an image on a large size recording medium.
A serial type inkjet recording apparatus records by scanning in a main scanning direction perpendicular to a direction in which the recording medium is conveyed (i.e., a sub-scanning direction). Such a serial type inkjet recording apparatus records the image using a recording head that moves along the recording medium. More specifically, the serial type recording apparatus records on the entire area of the recording medium by repeating an operation of conveying the recording medium by a predetermined amount each time the recording head ends recording once in the main scanning direction.
On the other hand, in a full line type inkjet recording apparatus, a recording width of the recording head corresponds to a width of the recording medium, and recording is performed only by a movement in the conveying direction of the recording medium. In such a full line type inkjet recording apparatus, the recording medium is set at a predetermined position, and the recording apparatus continuously records one line at a time by conveying the recording medium.
As a result, the full line type inkjet recording apparatus records on the entire area of the recording medium. The full line type inkjet recording apparatus is capable of forming the image at higher speed. In response, the full line type inkjet recording apparatus is receiving attention as a recording apparatus for performing on-demand recording, which is recently in high needs. Such a full line type inkjet recording apparatus is discussed in Japanese Patent Application Laid-Open No. 2002-292859.
If the full line type recording apparatus is to be used in on-demand recording, it generally is necessary to record on an A3 size recording medium at a print speed of 30 pages or more per minute with a high resolution of 600 dots per inch (dpi)×600 dpi or greater. Further, it generally is necessary to record a full-color image such as a photograph on the A3 size recording medium at the print speed of 30 pages or more per minute with a high resolution of 1200 dpi×1200 dpi or greater.
If the above-described full line type recording apparatus forms a high-duty image using one recording element array, ink droplets discharged from the adjacent recording elements undesirably may combine on the recording medium, depending on the amount of ink in the ink droplet. In such a case, an inappropriate shape may be formed on the recording medium, and may lead to deterioration of the formed image.
To solve such a problem, a multiple array head may be used as the recording head for the full line type inkjet recording apparatus. The multiple array head is a recording head having recording element arrays that discharge ink droplets of the same color and are arranged in parallel. The number of ink droplets discharged at the same time is reduced by discharging ink of the same color using multiple recording element arrays, so that combining of the ink droplets can be reduced.
In the full line type recording apparatus, the inkjet recording elements are positioned across the full-width of the recording area of the recording medium. Conventionally, these inkjet recording elements are difficult to manufacture without defect. In particular, it is currently difficult to manufacture without defect all discharge ports configuring a portion of the inkjet recording element.
For example, if the full line type recording apparatus is to record on the A3 size paper with a resolution of 1200 dpi, it is necessary to form approximately 14,000 discharge ports (recording width approximately 280 mm) in the full line type recording head. It is thus difficult to manufacture such a large number of discharge ports without defect. Even when such a recording head can be manufactured, yield rate becomes low and manufacturing cost becomes large.
To solve such a problem, an elongated joint head may be used as the full line type recording head. The joint head is a recording head in which recording chips are arranged in a direction of the discharge port arrays that are included in the recording chip. The recording elements are aligned in the discharge port array. In other words, the elongated recording head is formed by accurately arranging low cost short chips used in the serial type recording apparatus, to be connected in the direction in which the discharge port arrays are arranged.
The multiple array head and the joint head are described above as the recording heads for the full line type recording apparatus. The serial type recording apparatus also may use such recording heads for performing recording.
However, the above-described multiple array head may generate periodical density unevenness on the recording medium due to a periodical position change of the recording head with respect to the recording medium arising from the configuration thereof. The periodical density unevenness is a density change, which is generated periodically in a direction perpendicular to the direction in which the recording element arrays are arranged. In a case of the full line type printer, meandering of the recording medium when being conveyed generates the periodical position change of the recording head with respect to the recording medium. In the case of the serial type printer, vibration of the recording head generates the periodical position change.
FIG. 1 illustrates an example of the periodical position change of the multiple array head, i.e., the recording head, with respect to the recording medium. FIG. 2 illustrates an example of impact positions of the ink dots discharged from each of the recording elements in the recording head. FIG. 3 illustrates an example of a distance between the impact positions of the ink dots discharged from each of the recording elements in the recording head.
Referring to FIG. 1, the multiple array head, i.e., a recording head, includes a recording element P1 and a recording element P2. It is assumed that the positions of the recording element P1 and the recording element P2 with respect to the recording medium change in a sine wave shape as illustrated in FIG. 2. In such a case, the distance between the impact positions of the ink dots discharged from the recording element P1 and the recording element P2 changes according to the position in an X-direction as illustrated in FIG. 3.
Further, it is assumed that the recording element other than the recording element P1 in a recording element array 1 and the recording element in a recording element array 2, whose position in the X-direction is the same as the other recording element discharge the ink dots. In such a case, the distance between the impact positions similarly changes according to the position in the X-direction as illustrated in FIG. 3. Such a change in the distance causes the periodical density unevenness in the image recorded on the recording medium.
Furthermore, the above-described joint head tends to periodically generate a line on the recording medium at a joint portion by the periodical position change of the recording head with respect to the recording medium arising from the configuration thereof. Such a line is the density change that is periodically generated at the joint portion in the direction perpendicular to the direction in which the recording element arrays are arranged.
FIG. 4 is a schematic diagram illustrating an example of the periodical position change of the joint head, i.e., the recording head, with respect to the recording medium.
Referring to FIG. 4, it is assumed that the positions of the recording element P1 and the recording element P2 in the joint head with respect to the recording medium change in the sine wave shape as illustrated in FIG. 2. In such a case, the distance between the impact positions of the ink dots discharged from the recording element P1 and the recording element P2 changes according to the positions in the X-direction as illustrated in FIG. 3.
Further, it is assumed that the recording element other than the recording element P1 in the joint portion of the recording element array 1 illustrated in FIG. 4 and the recording element in the joint portion of the recording element array 2, whose position in the X-direction is the same as the other recording element discharge ink dots. In such a case, the distance between the impact positions similarly changes according to the position in the X-direction as illustrated in FIG. 3. The change of distance causes periodic line in the image recorded on the recording medium at the joint portion.